Recent studies on RR ' S center dot C2B9H11 charge-compensated ligands - Crystal structures of 10-(S(CH3)(2))-7,8-C2B9H11 and 10-(S(CH2)(4))-7,8-C2B9H11

摘要

In this paper we report the synthesis of three new carborane derivatives of the series 7,8-R,R'-10-L-7,8-C2B9H9 (R = R'= H, L = SEtPh; R = CH3, R' = H, L = SMe2 and L = SEt2) along with the enhanced characterization of formerly described compounds 7,8-R,R'-10-L-7,8-C2B9H9 (R = R'= H, L = SMe2 (1), L = SEt2 (2) and L = S(CH2)(4) (3)). They have been fully characterised using H-1-, B-11- and C-13-NMR spectroscopy. Their bridging proton resonances have been located for the first time. Individual sulfonium substituent contributions have been calculated that have permitted to establish a rule to predict its position in the H-1-NMR spectrum. The crystal structures of 1 and 3 have been resolved for the first time. Themolysis of 1, 2 and 3 in aromatic solvents at reflux temperature yielded a mixture of the corresponding 9-substituted derivative via isomerisation and 2,3-closo-C2B9H11 via elimination of SR2. This reaction has been demonstrated to be tuneable upon convenient choice of the aromatic solvent, the ligand and the reaction time, leading to a new and more straightforward preparation of the series 9-L-7,8-nido-C2B9H9 and the cluster 2,3-closo-C2B9H11. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved. [References: 27]